The invention relates generally to substrate processing, and in one embodiment, to a system and method for securing a three dimensional semiconductor substrate during one or more processing operations.
Conventional integrated circuits, or xe2x80x9cchipsxe2x80x9d, normally require processing at multiple facilities, being manufactured as flat surface semiconductor wafers in a specialized manufacturing facility, and then transferred to a fabrication facility, where several layers are processed onto the wafer. The wafer is then cut into one or more chips and assembled into packages. The enormous effort and expense required for creating perfectly flat silicon wafers hampers the process of creating chips. High manufacturing costs make the chips expensive. For example, dust-free clean rooms and temperature-controlled manufacturing and storage areas are necessary to prevent the wafers and chips from warping. Moreover, the wafers typically have some defects in spite of all the precautions taken, due to the difficulty in making a large, single, highly pure crystal.
As the demand for smaller electronic devices continues, integrated circuits must become smaller, and the above-described wafer defects will become more significant. As such, alternatives to chips will play an increasingly important role in the future. For example, U.S. Pat. No. 5,955,776, which is hereby incorporated by reference, discloses a method and apparatus for manufacturing a spherical-shaped semiconductor integrated circuit having many benefits over chips.
Spherical-shaped semiconductor fabrication includes a variety of processing steps, including deposition of films and photolithography. Many of these processing steps require that the semiconductor substrate be rigidly secured. For example, photolithography requires that the substrate be relatively still and in a predetermined location. Such securement becomes even more important as the xe2x80x9cqualityxe2x80x9d of the photolithography increases, such as with highly intricate circuit patterns with very small critical dimensions.
Therefore, what is needed is a system and method to help secure three-dimensional substrates for processing operations such as lithography.
The present invention provides a system and method to help secure a small three dimensional substrate, such as a spherical shaped semiconductor substrate, for processing operations, such as lithography. In one embodiment, the method secures the substrate by positioning it proximate to a member and applying an adhering substance, such as photo resist, to the substrate and a portion of the member. The adhering substance securely attaches the substrate to the member so that one or more processing operations may be performed on the substrate.
In some embodiments, after processing, the adhering substance is removed to facilitate separating the member from the substrate.
In some embodiments, the substrate is positioned proximate to the member by applying a selectively attachable force between the substrate and member. For example, the selectively attachable force may be a vacuum.
In another embodiment, the method may be used for performing lithography on the spherical substrate, by releasably attaching the substrate to the member and inserting the substrate and a portion of the member into a supply of photo resist. The photo resist may then be electronically deposited to the substrate and to the portion of the member so that the photo resist rigidly secures the substrate to the member. Once rigidly secured, lithography can be performed on the spherical substrate.
In some embodiments, after performing lithography, the photo resist can be removed from the substrate and the member so that the substrate can be released from the member.
In some embodiments, the step of inserting the substrate and the member into a supply of photo resist includes submersing the substrate and the member portion into a container of the photo resist.
In some embodiments, the member may be electrically conductive and electrically connected to the substrate. In these embodiments, the step of electronically depositing may include attaching a first terminal of an electrical source to the member and a second terminal of the electrical source to the container of the photo resist. A voltage differential can thereby be created between the member and the second terminal to facilitate electro-deposition.
As a result, the substrate is secured to the member in a relatively simple and very effective way. Benefits can be seen from such a system and method by examining the attached drawings and following description.